Adhesive composition and adhesive optical component using the composition

ABSTRACT

An adhesive sheet including an adhesive composition disposed on at least one face of a film of acetyl cellulose, the adhesive sheet being produced by coating a solution of the adhesive composition on the face of the film and drying the solution to form a laminate, the adhesive composition containing (A) a copolymer of (meth)acrylic esters,(B) a crosslinking agent and (C) a phenol compound. The adhesive composition in the adhesive sheet serves to suppress degradation of easily hydrolyzable materials by hydrolysis, improve durability and provides excellent stress relaxation without using plasticizers.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a Divisional application of application Ser.No. 09/829,061, filed Apr. 9, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an adhesive composition and anadhesive optical component using the adhesive composition. Moreparticularly, the present invention relates to an adhesive compositionwhich, by application to easily hydrolyzable materials such assubstrates and adherends, suppresses degradation of the materials byhydrolysis and improves durability of the materials; an adhesivecomposition which provides excellent stress relaxation withoutplasticizers, suppresses degradation of easily hydrolyzable materialssuch as substrates and adherents by hydrolysis by application to thematerial, suppresses degradation of the composition itself and givesadhesive optical components having excellent quality; and an adhesiveoptical component comprising the adhesive composition such as apolarizing plate and a plate for phase differentiation.

[0004] 2. Description of Related Art

[0005] As the adhesive, acrylic adhesives, polyurethane adhesives,polyester adhesives, rubber adhesives and silicone adhesives haveheretofore been used. Among these adhesives, acrylic adhesives arewidely used. An acrylic adhesive contains, in general, a copolymer of(meth)acrylic esters and a crosslinking agent. As the copolymer of(meth)acrylic esters, for example, a copolymer of a (meth)acrylic estersuch as butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl(meth)acrylate and decyl (meth)acrylate with a functional monomer forforming crosslinking points is used. The functional monomer is,specifically, a functional monomer having hydroxyl group such ashydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate or afunctional monomer having carboxyl group such as (meth)acrylic acid,maleic acid, crotonic and itaconic acid.

[0006] However, when the acrylic adhesive is applied to a material whichis easily hydrolyzed such as films of cellulose acetate, a problemarises in that the material tends to be hydrolyzed due to the effect ofcarboxyl group in the copolymer of (meth)acrylic esters contained in theacrylic adhesive. The degradation of the material by hydrolysis takesplace markedly, in particular, under an environment of a hightemperature and high humidity.

[0007] Some optical components are used after a polarizing plate isattached to the surface. Typical examples of such optical componentsinclude liquid crystal cells in liquid crystal displays (LCD). Ingeneral, a liquid crystal cell has a structure in which two transparentelectrode substrates having an oriented layer are placed in a mannersuch that a specific gap is formed between them with a spacer and theoriented layers face to each other at the inside, peripheral portions ofthe transparent electrode substrates are sealed, a liquid crystallinematerial is placed and held inside the gap between the transparentelectrode substrates and a polarizing plate is disposed on each outersurface of the two transparent electrode substrates via an adhesivelayer.

[0008]FIG. 1 shows a perspective view exhibiting the structure of anexample of the polarizing plate described above. As shown in FIG. 1, thepolarizing plate 10 has a substrate having a three-layer structure inwhich triacetylcellulose (TAC) film I 2 and TAC film II 2′ are laminatedon the faces of a polarizing plate 1 made of polyvinyl alcohol. On oneface of the substrate, an adhesive layer 3 for sticking the substrate toan optical component such as a liquid crystal cell is formed. A releasesheet 4 is attached to the adhesive layer 3. In general, a film forprotecting the surface 5 is disposed on the face of the polarizing plateopposite to the face having the adhesive layer 3.

[0009] When the above polarizing plate is attached to the above liquidcrystal cell, the release sheet 4 is removed first, then the polarizingplate is stuck to the liquid crystal cell via the exposed adhesive layerand the film for protecting the surface 5 is removed.

[0010] For the adhesive layer disposed on the polarizing plate, acrylicadhesives are widely used. However, as described above, the acrylicadhesive promotes hydrolysis of the TAC film of the polarizing plate dueto the effect of carboxyl group in the copolymer of (meth)acrylic estersand the polarizing plate is degraded. The degradation of the polarizingplate takes place markedly, in particular, under an environment of ahigh temperature and a high humidity.

[0011] In liquid crystal display apparatuses of the STN type, it iswidely conducted that a plate for phase differentiation is disposedbetween a liquid crystal cell and a polarizing plate. As the plate forphase differentiation, in general, a laminate having a TAC film on oneor both faces of a stretched film of polyvinyl alcohol and a layer of anacrylic adhesive on the face of the TAC film, is used. An liquid crystalcell is formed by laminating one or a plurality of plates for phasedifferentiation to an STN cell via the above adhesive layer and thenlaminating a polarizing plate on the outermost layers. The thus preparedliquid crystal cell also has a problem in that degradation of the TACfilm by hydrolysis takes place in the plate for phase differentiationsimilarly to the degradation of the TAC film in the polarizing plate.

[0012] To overcome the above problems, for example, a method in whichthe amount of carboxyl group contained in the adhesive is decreased(Japanese Patent Application Laid-Open No. Showa 59(1984)-111114) and amethod in which a tertiary amine is added (Japanese Patent ApplicationLaid-Open No. Heisei 4(1992)-254803) have been proposed. However, themethod in which the amount of carboxyl group is decreased has a drawbackin that the excellent balance between the physical properties of theadhesive is inevitably lost and the method in which a tertiary amine isadded has a drawback in that the pot life of the adhesive decreasessince control of the reactions between a crosslinking agent and variousfunctional groups in the adhesive becomes difficult and workability invarious steps deteriorates.

[0013] The polarizing plate which is attached to the liquid crystal cellvia the adhesive layer has the three-layer structure described above.Due to the properties of the materials, the polarizing plate has poordimensional stability and, in particular, change in the dimension bycontraction or expansion is great in the environment of a hightemperature or a high temperature and a high humidity.

[0014] However, since, in general, an adhesive having a great adhesiveability is used in the above polarizing plate, stress caused by thechange in the dimension of the polarizing plate cannot be absorbed andrelaxed by the adhesive layer although lifting and peeling caused by thechange in the dimension of the polarizing plate can be suppressed. Morespecifically, in FIG. 1, TAC film II 2′ at the front face tends tocontract or expand due to change in the humidity and the temperature. Onthe other hand, TAC film I 2 cannot not contract or expand easily sinceTAC film I is firmly adhered to the liquid crystal cell via the adhesivelayer 3 and the adhesive layer cannot flexibly follow the change in thedimension. As the result, ray passing through TAC film I toward TAC filmII cannot proceed straight. This causes undesirable phenomena such asleak of light.

[0015] To overcome the above problems, heretofore, a plasticizer isadded to the adhesive so that the adhesive is flexible to a suitabledegree and stress relaxation takes place. However, the adhesivecontaining a plasticizer has drawbacks in that the plasticizer bleedsout and that the adherend is stained with the plasticizer when thepolarizing plate is peeled by the bleeding out. When a polyfunctionalcrosslinking agent having a functionality of three or greater is used inan adhesive, the number of crosslinks in the adhesive is decreased.However, the holding ability, i.e., the adhesion with the adherend,inevitably decreases in this case and problems such as lifting andpeeling of the polarizing plate tend to arise with passage of the time.

[0016] Intensive studies on adhesive compositions exhibiting excellentstress relaxation without adding plasticizers have been made by thepresent inventors to overcome the above problems and it was found thatexcellent stress relaxation can be exhibited by using a copolymer of(meth)acrylic esters having a great molecular weight and an oligomer of(meth)acrylic esters having a small molecular weight in combination.However, when this adhesive composition is applied to a polarizing plateand the like, it was found that an undesirable phenomenon occasionallytook place in that brightness was different at portions around the edgesand at other portions of the polarizing plate.

[0017] Moreover, a problem takes place in the acrylic adhesive in thatthe molecular weight of the copolymer of (meth)acrylic esters decreasesince degradation takes place under a condition of a high temperatureand a high humidity although the degradation proceeds slowly. As theresult, cohesive force in the adhesive becomes insufficient and liftingand peeling take place between a substrate such as a polarizing plateand a plate for phase differentiation and an adherend such as a plate ofglass or polycarbonate.

SUMMARY OF THE INVENTION

[0018] Under the above circumstances, the present invention has a firstobject of providing an adhesive composition which suppresses degradationof easily hydrolyzable materials by hydrolysis and improves durabilityof the materials when the adhesive composition is applied to thematerials; a second object of providing an adhesive composition whichprovides excellent stress relaxation without plasticizers, suppressesdegradation of easily hydrolyzable materials by hydrolysis when theadhesive composition is applied to the materials, suppresses degradationof the composition itself and gives adhesive optical components havingexcellent quality; and a third object of providing an adhesive opticalcomponents such as a polarizing plate and a plate for phasedifferentiation which comprise a layer of the above adhesivecomposition.

[0019] As the result of intensive studies by the present inventors toachieve the above objects, it was found that the first object can beachieved with an adhesive composition comprising a copolymer of(meth)acrylic esters, a crosslinking agents and a phenol derivative,that the second object can be achieved with an adhesive compositioncomprising a copolymer of (meth)acrylic esters or, preferably, a mixtureof a copolymer of (meth)acrylic esters and an oligomer of (meth)acrylicesters, a crosslinking agent, a radical scavenger and, optionally, asecondary antioxidant and that the third object can be achieved bydisposing a layer comprising the adhesive composition obtained asdescribed above at least on one face of an optical component.

[0020] The present invention has been completed based on the aboveknowledge.

[0021] The present invention provides:

[0022] (1) An adhesive composition which comprises (A) a copolymer of(meth)acrylic esters, (B) a crosslinking agent and (C) a phenolderivative (referred to as adhesive composition I, hereinafter);

[0023] (2) An adhesive optical-component comprising an optical componentand a layer which comprises adhesive composition I and is disposed atleast on one face of the optical component (referred to as Adhesiveoptical component I, hereinafter);

[0024] (3) An adhesive composition which comprises (D) a copolymer of(meth)acrylic esters having a weight-average molecular weight of 500,000to 2,500,000, (E) a crosslinking agent and (F) a radical scavenger(referred to as adhesive composition II, hereinafter);

[0025] (4) An adhesive composition which comprises (D′) a mixture of acopolymer of (meth)acrylic esters having a weight-average molecularweight of 500,000 to 2,500,000 and an oligomer of (meth)acrylic estershaving a weight-average molecular weight of 1,000 to 10,000 in amountssuch that a ratio of the amounts by weight of the copolymer to theoligomer is in a range of 100:5 to 100:100, (E) a crosslinking agent and(F) a radical scavenger (referred to as adhesive composition II′,hereinafter); and

[0026] (5) An adhesive optical component comprising an optical componentand a layer which comprises any of adhesive compositions II and II′ andis disposed at least on one face of the optical component (referred toas Adhesive optical component II, hereinafter)

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1 shows a perspective view exhibiting the structure of anexample of a polarizing plate.

[0028] In the figure, 1 means a polarizing plate made of polyvinylalcohol, 2 means TAC film I, 2′ means TAC film II, 3 means an adhesivelayer, 4 means a release sheet, 5 means a film for protecting thesurface and 10 means a polarizing plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Adhesive composition I of the present invention will be describedin the following.

[0030] Adhesive composition I of the present invention comprises acopolymer of (meth)acrylic esters as component (A), a crosslinking agentas component (B) and a phenol derivative as component (C).

[0031] As the copolymer of (meth)acrylic esters of component (A),copolymers having portions for crosslinking which can be crosslinkedwith the crosslinking agent of component (B) are used. The copolymer of(meth)acrylic ester having such portions for crosslinking is notparticularly limited. A copolymer can be suitably selected fromcopolymers of (meth)acrylic esters which are conventionally used as theresin component of adhesives.

[0032] Preferable examples of the copolymer of (meth)acrylic esterhaving such portions for crosslinking include copolymers of a(meth)acrylic ester in which the alkyl group in the ester portion has 1to 20 carbon atoms, a monomer having a functional group having an activehydrogen and other monomers which are used where desired.

[0033] Examples of the copolymer of a (meth)acrylic ester in which thealkyl group in the ester portion has 1 to 20 carbon atoms include methyl(meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl(meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl(meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate,decyl (meth)acrylate, dodecyl (meth)acrylate, myristyl (meth)acrylate,palmityl (meth)acrylate and stearyl (meth)acrylate. The copolymers of a(meth)acrylic ester may be used singly or in combination of two or more.

[0034] Examples of the monomer having a functional group having anactive hydrogen include hydroxyalkyl esters of (meth)acrylic acid suchas 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate,3-hydroxybutyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate;acrylamides such as acrylamide, methacrylamide, N-methylacrylamide,N-methylmethacrylamide, N- methylolacrylamide andN-methylol-methacrylamide; monoalkylaminoalkyl (meth)acrylates such asmonomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate,monomethylaminopropyl (meth)acrylate and monoethylaminopropyl(meth)acrylate; and ethylenically unsaturated carboxylic acids such asacrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconicacid and citraconic acid. The above monomers may be used singly or incombination of two or more.

[0035] Examples of the other monomers which are used where desiredinclude vinyl esters such as vinyl acetate and vinyl propionate; olefinssuch as ethylene, propylene and isobutylene; halogenated olefins such asvinyl chloride and vinylidene chloride; styrenic monomers such asstyrene and α-methylstyrene; diene monomers such as butadiene, isopreneand chloroprene; nitrile monomers such as acrylonitrile andmethacrylonitrile; and N,N-dialkylsubstituted acrylamides such asN,N-dimethylacrylamide and N,N-dimethylmethacrylamide. The abovemonomers may be used singly or in combination of two or more.

[0036] In adhesive composition I of the present invention, the structureof the copolymer of (meth)acrylic esters used as component (A) is notparticularly limited and any of random copolymers, block copolymers andgraft copolymers can be used. As for the molecular weight, it ispreferable that the weight-average molecular weight is in the range of500,000 to 2,500,000. When the weight-average molecular weight issmaller than 500,000, there is the possibility that adhesion anddurability of adhesion with the adherend are insufficient. When theweight-average molecular weight exceeds 2,500,000, the property offollowing change in the dimension of the substrate may deteriorate. Fromthe standpoint of adhesion, durability of adhesion and the property offollowing change in the dimension of the substrate, it is preferablethat the weight-average molecular weight is 800,000 to 1,800,000 andmore preferably 1,200,000 to 1,600,000.

[0037] The weight-average molecular weight described above is theweight-average molecular weight of the corresponding polystyreneobtained in accordance with the gel permeation chromatography (GPC).

[0038] In the present invention, the copolymer of (meth)acrylic estersof component (A) may be used singly or in combination of two or more.Where desired, homopolymers and copolymers of (meth)acrylic estershaving a small molecular weight such as a weight-average molecularweight of 100,000 or smaller can be used in combination with the abovecopolymer of (meth)acrylic esters having a great molecular weight.

[0039] The crosslinking agent of component (B) in adhesive composition Iof the present invention is not particularly limited. A compound can besuitably selected from crosslinking agents which are conventionally usedin acrylic adhesives. Examples of the crosslinking agent includepolyisocyanate compounds, epoxy resins, melamine resins, urea resins,dialdehydes and methylol polymers. In the present invention,polyisocyanate compounds are preferably used.

[0040] Examples of the polyisocyanate compound include aromaticpolyisocyanates such as tolylene diisocyanate, diphenylmethanediisocyanate and xylylene diisocyanate; aliphatic polyisocyanates suchas hexamethylene diisocyanate; alicyclic polyisocyanates such asisophorone diisocyanate and hydrogenated diphenylmethane diisocyanate;biuret compounds and isocyanurate compounds derived from the abovepolyisocyanates; and adduct compounds which are reaction products of theabove polyisocyanates with low molecular weight compounds having anactive hydrogen such as ethylene glycol, propylene glycol, neopentylglycol, trimethylolpropane and castor oil.

[0041] In the present invention, the crosslinking agent of component (B)may be used singly or in combination of two or more. The amount isselected, in general, in the range of 0.001 to 50 parts by weight andpreferably in the range of 0.01 to 10 parts by weight per 100 parts byweight of the copolymer of acrylic esters of component (A) although theamount may be different depending on the type of the crosslinking agent.

[0042] In adhesive composition I of the present invention, a phenolderivative is used as component (C). The phenol derivative is used forsuppressing hydrolysis of the easily hydrolyzable material such as afilm of acetylcellulose to which the adhesive composition of the presentinvention is applied.

[0043] As the phenol derivative, it is preferable that at least onecompound is suitably selected, for example, from single ring phenolcompounds, two-ring phenol compounds, three-ring phenol compounds andfour-ring phenol compounds.

[0044] Examples of the phenol derivative include single ring phenolcompounds such as 2,6-di-tert-butyl-p-cresol, butylhydroxyanisole andstearyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; two-ring phenolcompounds such as 4,4′-butylidenebis(3-methyl-6-tert-butylphenol) and3,6-dioxaoctamethylenebis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]; three-ring phenol compounds such as1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane; and four-ringphenol compounds such astetrakis[methylene-3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate]-methane.

[0045] In the present invention, the amount of the phenol derivative ofcomponent (C) is selected, in general, in the range of 0.01 to 10 partsby weight per 100 parts by weight of the copolymer of (meth)acrylicesters of component (A). When the amount is less than 0.01 part byweight, there is the possibility that the effect of suppressinghydrolysis is not sufficiently exhibited and the object of the presentinvention is not achieved. When the amount exceeds 10 parts by weight,the effect of suppressing hydrolysis is not exhibited to the degreeexpected from the used amount. Moreover, economic disadvantage arisesand physical properties of adhesion may be adversely affected. From thestandpoint of the effect of suppressing hydrolysis, the physicalproperties of adhesion and the economy, it is preferable that the amountof the phenol derivative is in the range of 0.05 to 5 parts by weightand more preferably in the range of 0.1 to 2 parts by weight.

[0046] Adhesive composition I of the present invention may furthercomprise various additives conventionally used for adhesive compositionssuch as plasticizers, silane coupling agents and ultraviolet absorbentsas long as the additives do not adversely affect the objects of thepresent invention, where desired.

[0047] When a silane coupling agent, among the above additives, is addedto the adhesive composition, adhesion to a liquid crystal cell (glass)under a hot and humid condition is improved and lifting and peeling ofthe polarizing plate and the plate for phase differentiation aresuppressed. As the silane coupling agent, organic silicon compoundswhich have at least one alkoxysilyl group in the molecule, arecompatible with the components of the adhesive composition and transmitlight are preferably used. For example, substantially transparentorganic silicon compounds having these properties are used. Examples ofthe silane coupling agent include vinyltriethoxysilane,vinyltris(2-methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane,2-(3,4epoxycyclohexyl)ethyltrimethoxysilane,3-aminopropyltriethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane.It is preferable that the amount of the silane coupling agent is in therange of 0.001 to 10 parts by weight and more preferably in the range of0.005 to 5 parts by weight per 100 parts by weight of the adhesivecomposition.

[0048] When adhesive composition I of the present invention having theabove composition is applied to easily hydrolyzable materials,degradation of the materials by hydrolysis is suppressed and, inparticular, durability under a high temperature and a high humidity canbe improved. Therefore, adhesive composition I is advantageously appliedto films of acetylcellulose which are easily hydrolyzed.

[0049] Adhesive compositions II and II′ of the present invention will bedescribed in the following.

[0050] In adhesive composition II, a copolymer of (meth)acrylic estersalone is used as component (D) and, in adhesive composition II′, amixture of a copolymer of (meth)acrylic esters and an oligomer of(meth)acrylic esters is used as component (D′).

[0051] As the copolymer of (meth)acrylic esters of component (D), acopolymer of (meth)acrylic esters having portions for crosslinking whichcan be crosslinked with the crosslinking agent of component (E) is used.The copolymer of (meth)acrylic esters having portions for crosslinkingis not particularly limited. A copolymer can be suitably selected fromcopolymers of (meth)acrylic esters which are conventionally used as theresin component of adhesive compositions.

[0052] Preferable examples of the copolymer of (meth)acrylic estershaving portions for crosslinking include copolymers of a (meth)acrylicester in which the alkyl group in the ester portion has 1 to 20 carbonatoms, a monomer having a functional group having an active hydrogen andother monomers which are used where desired.

[0053] Examples of the (meth)acrylic ester in which the alkyl group inthe ester portion has 1 to 20 carbon atoms, the monomer having afunctional group having an active hydrogen and the other monomers whichare used where desired include the (meth)acrylic ester in which thealkyl group in the ester portion has 1 to 20 carbon atoms, the monomerhaving a functional group having an active hydrogen and the othermonomers which are used where desired, respectively, which are describedas the examples of the components for the copolymer of (meth)acrylicesters of component (A) used in adhesive composition I.

[0054] In adhesive composition II of the present invention, thestructure of the copolymer of (meth)acrylic esters used as component (D)is not particularly limited and any of random copolymers, blockcopolymers and graft copolymers can be used. The weight-averagemolecular weight of the copolymer is selected in the range of 500,000 to2,500,000. When the weight-average molecular weight is smaller than500,000, there is the possibility that adhesion and durability ofadhesion with the adherend are insufficient. When the weight-averagemolecular weight exceeds 2,500,000, the property of following change inthe dimension of the substrate may deteriorate. From the standpoint ofadhesion, durability of adhesion and the property of following change inthe dimension of the substrate, it is preferable that the weight-averagemolecular weight is 800,000 to 1,800,000 and more preferably 1,200,000to 1,600,000.

[0055] The weight-average molecular weight described above is theweight-average molecular weight of the corresponding polystyreneobtained in accordance with the gel permeation chromatography (GPC).

[0056] In the present invention, the copolymer of (meth)acrylic estersof component (D) may be used singly or in combination of two or more.

[0057] In adhesive composition II′ of the present invention, a mixtureof the copolymer of (meth)acrylic esters described above and an oligomerof (meth)acrylic esters can be used as component (D′) so that stressrelaxation is provided.

[0058] The oligomer of (meth)acrylic ester may be any oligomer selectedfrom oligomers obtained by homopolymerizing one compound selected from(meth)acrylic esters in which the alkyl group in the ester portion has 1to 20 carbon atoms, oligomers obtained by copolymerizing at least twocompounds selected from the above (meth)acrylic esters and oligomersobtained by copolymerizing at least one compound selected from the above(meth)acrylic esters with other monomers.

[0059] Examples of the (meth)acrylic ester in which the alkyl group inthe ester portion has 1 to 20 carbon atoms and the other monomersinclude the (meth)acrylic esters in which the alkyl group in the esterportion has 1 to 20 carbon atoms and the other monomers, respectively,which are described as the examples of the components for the copolymerof (meth)acrylic esters of component (A) used in adhesive composition I.

[0060] The weight-average molecular weight of the oligomer of(meth)acrylic esters is selected in the range of 1,000 to 10,000. Whenthe molecular weight is smaller than 1,000, the oligomer bleeds out andthere is the possibility that an adherend is stained when a substrateadhered to the adherend via the adhesive composition is removed. Whenthe molecular weight exceeds 10,000, there is the possibility that theproperty of following change in the dimension of the substrate (stressrelaxation) of the adhesive composition deteriorates. From thestandpoint of preventing staining of the adherend and the property offollowing change in the dimension of the substrate, it is preferablethat the weight-average molecular weight of the oligomer of(meth)acrylic esters is in the range of 3,000 to 10,000.

[0061] It is preferable that the oligomer of (meth)acrylic esters has aratio of the weight-average molecular weight (Mw) to the number-averagemolecular weight (Mn) representing the molecular weight distribution of2.0 or smaller. When the ratio Mw/Mn exceeds 2.0, there is thepossibility that the oligomer contains components having excessivelysmall molecular weights. Such components may cause bleeding out of theoligomer and staining of an adherend when a substrate adhered to theadherend via the adhesive composition is removed. It is more preferablethat the ratio Mw/Mn is 1.7 or smaller.

[0062] The weight-average molecular weight and the number-averagemolecular weight described above are the weight-average molecular weightand the number-average molecular weight, respectively, of thecorresponding polystyrene obtained in accordance with GPC.

[0063] In the present invention, the oligomer of (meth)acrylic estersmay be used singly or in combination of two or more.

[0064] In adhesive composition II′ of the present invention, theoligomer of (meth)acrylic esters is used in an amount of 5 to 100 partsby weight per 100 parts by weight of the above copolymer of(meth)acrylic esters. When the amount of the oligomer is less than 5parts by weight, the property of following change in the dimension ofthe substrate (stress relaxation) becomes insufficient. When the amountof the oligomer exceeds 100 parts by weight, adhesion with the adherendbecomes poor. From the standpoint of the property of following change inthe dimension of the substrate and adhesion with the adherend, it ispreferable that the amount of the oligomer is in the range of 10 to 70parts by weight and more preferably in the range of 15 to 50 parts byweight.

[0065] In adhesive compositions II and II′, the crosslinking agent ofcomponent (E) is not particularly limited. A crosslinking agent can besuitably selected from conventional crosslinking agents used for acrylicadhesives. Examples of the crosslinking agent include the compoundsdescribed as the examples of the crosslinking agent of component (B) inadhesive composition I.

[0066] In the present invention, the crosslinking agent of component (E)may be used singly or in combination of two or more. The amount of thecrosslinking agent is selected, in general, in the range of 0.001 to 50parts by weight and preferably in the range of 0.01 to 10 parts byweight per 100 parts by weight of the copolymer of (meth)acrylic estersof component (D) or the copolymer of (meth)acrylic esters in component(D′) although the amount may be varied depending on the type of thecrosslinking agent.

[0067] Adhesive compositions II and II′ comprises a radical scavenger ascomponent (F).

[0068] The radical scavenger is a compound which scavenges radicalsgenerated by heat or light or with a heavy metal, suppresses initiationof chain reactions and inhibits chain reactions of the radicals. Sinceadhesive compositions II and II′ of the present invention comprise theradical scavenger, the following effects are exhibited:

[0069] (1) When adhesive compositions II and II′ are applied to aneasily hydrolyzable material such as a film of acetyl cellulose,hydrolysis of the material is suppressed.

[0070] (2) Degradation of the adhesive itself is suppressed and, evenwhen an optical component in which the adhesive composition of thepresent invention is used is left standing under a condition of a hightemperature and a high humidity, lifting and peeling are not easilyformed.

[0071] (3) When a copolymer of (meth)acrylic esters having a greatmolecular weight and an oligomer of (meth)acrylic esters having a smallmolecular weight are used in combination so that stress relaxation isexhibited, formation of uneven brightness can be suppressed in apolarizing plate to which the adhesive composition of the presentinvention is applied.

[0072] In the present invention, antioxidants, amine photostabilizersand polymerization inhibitors are preferably used as the radicalscavenger.

[0073] As the antioxidant, phenolic antioxidants are preferable.Examples of the phenolic antioxidant include single ring phenolcompounds such as 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-ethylphenol,2,6-dicyclohexyl-4-methylphenol, 2,6-diisopropyl-4-ethylphenol,2,6-di-t-amyl-4-methylphenol, 2,6-di-t-octyl-4-n-propylphenol,2,6-dicyclohexyl-4-n-octylphenol, 2-isopropyl-4-methyl-6-t-butylphenol,2-t-butyl-4-ethyl-6-t-octylphenol, 2-isobutyl-4-ethyl-6-t-hexylphenol,2-cyclohexyl-4-n-butyl-6-isopropylphenol, mixed cresol modified withstyrene, DL-α-tocopherol and stearylβ-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; two-ring phenol compoundssuch as 2,2′-methylenebis(4-methyl-6-t-butylphenol),4,4′-butylidenebis(3-methyl-6-t-butylphenol),4,4′-thiobis(3-methyl-6-t-butyl-phenol),2,2′-thiobis(4-methyl-6-t-butylphenol),4,4′-methylenebis(2,6-di-t-butylphenol),2,2′-methylenebis[6-(1-methylcyclohexyl)-p-cresol], 2,2′-ethylidenebis(4,6-di-t-butylphenol), 2,2′-butylidenebis(2-t-butyl-4-methylphenol),3,6-dioxaoctamethylenebis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], triethyleneglycolbis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediolbis[3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate] and2,2′-thiodiethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate];three ring phenol compounds such as 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane,1,3,5-tris(2,6-dimethyl-3-hydroxy-4-t-butylbenzyl) isocyanurate,1,3,5-tris[(3,5-di-t-butyl-4-hydroxy-phenyl)propionyloxyethyl]isocyanurate, tris(4-t-butyl-2,6-dimethyl-3-hydroxybenzyl) isocyanurateand 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene;four-ring phenol compounds such astetrakis-[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane; and phenol compounds containing phosphorus such asbis(ethyl 3,5-di-t-butyl-4-hydroxybenzylphosphonate) potassium andbis(ethyl 3,5-di-t-butyl-4-hydroxybenzylphosphonate) nickel.

[0074] Examples of the amine photostabilizer includebis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, polycondensates ofdimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine,tetrakis-(2,2,6,6-tetramethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate, 2,2,6,6-tetramethyl-4-piperidylbenzoate, bis(1,2,6,6-pentamethyl-4-piperidyl)2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butyl malonate,bis(N-methyl-2,2,6,6-tetramethyl-4-piperidyl) sebacate,1,1′-(1,2-ethandiyl)-bis(3,3,5,5-tetramethylpiperadinone), (mixed2,2,6,6-tetramethyl-4-piperidyl/tridecyl)1,2,3,4-butanetetracarboxylate, (mixed1,2,2,6,6-pentamethyl-4-piperidyl/-tridecyl)1,2,3,4-butanetetracarboxylate, mixed[2,2,6,6-tetramethyl-4-piperidyl/β,β,β′,β′-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro-(5,5)undecane]-diethyl]1,2,3,4-butanetetracarboxylate, mixed[1,2,2,6,6-pentamethyl-4-piperidyl/β,β,β′,β′-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro-(5,5)undecane]-diethyl 1,2,3,4-butanetetracarboxylate, condensates ofN,N′-bis(3-aminopropyl)ethylenediamine and2,4-bis[N-butyl-N-(1,2,2,6,6-penta-methyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine,poly[6-N-morpholyl-1,3,5-triazin-2,4-yl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imide],condensates of N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and1,2-dibromoethane and[N-(2,2,6,6-tetramethyl-4-piperidyl)-2-methyl-2-(2,2,6,6-tetramethyl-4-piperidyl)imino]propionamide.

[0075] The polymerization inhibitor is an agent conventionally used asthe polymerization inhibitor in radical polymerization. Examples of thepolymerization inhibitor include divalent phenolic polymerizationinhibitors such as hydroquinone, p-methoquinone, t-butylhydroquinone andt-butylcatechol; and phenothiazine.

[0076] In the present invention, the radical scavenger of component (F)may be used singly or in combination of two or more. The amount of theradical scavenger is selected, in general, in the range of 0.01 to 10parts by weight per 100 parts by weight of component (D) or component(D′). When the amount is less than 0.01 part by weight, there is thepossibility that the effect of the radical scavenger is not sufficientlyexhibited and the object of the present invention is not achieved. Whenthe amount exceeds 10 parts by weight, the effect of the radicalscavenger is not exhibited to the degree expected from the used amount.Moreover, economic disadvantage arises and physical properties ofadhesion may be adversely affected. From the standpoint of the effect ofthe radical scavenger, the physical properties of adhesion and theeconomy, it is preferable that the amount of the radical scavenger is inthe range of 0.05 to 5 parts by weight and more preferably in the rangeof 0.1 to 2 parts by weight.

[0077] When an antioxidant is used as the radical scavenger of component(F), a polymerizable antioxidant may be used in a manner such that thepolymerizable antioxidant is copolymerized in the preparation of thecopolymer of (meth)acrylic esters of component (D) or the copolymer of(meth)acrylic esters in component (D′) so that the unit of thepolymerizable antioxidant is incorporated into the prepared copolymer.In this case, the content of the unit of the polymerizable antioxidantis selected, in general, in the range of 0.01 to 10 parts by weight,preferably in the range of 0.05 to 5 parts by weight and most preferablyin the range of 0.1 to 2 parts by weight per 100 parts by weight of thetotal amount of component (D) or component (D′). By incorporating thepolymerizable antioxidant into the copolymer, the antioxidant does noteasily vaporize and an adhesive composition exhibiting excellentdurability can be obtained.

[0078] Examples of the polymerizable antioxidant include compounds (a),(b) and (c) having the following structures:

[0079] Compound (a) and compound (b) are commercially available as“SUMILIZER GM” [manufactured by SUMITOMO KAGAKU KOGYO Co., Ltd.] and“SUMILIZER GS” [manufactured by SUMITOMO KAGAKU KOGYO Co., Ltd.],respectively.

[0080] In adhesive compositions II and II′, a secondary antioxidant maybe used as component (G) in combination with the radical scavenger ofcomponent (F). When the radical scavenger is used alone, there is thepossibility that the radical scavenger itself causes coloring. Thesecondary antioxidant is used to suppress the coloring.

[0081] Examples of the secondary antioxidant include antioxidantscontaining phosphorus and antioxidants containing sulfur.

[0082] Examples of the antioxidant containing phosphorus includetrioctyl phosphite, trilauryl phosphite, tristridecyl phosphite,trisisodecyl phosphite, phenyl diisooctyl phosphite, phenyl diisodecylphosphite, phenyl di(tridecyl) phosphite, diphenyl isooctyl phosphite,diphenyl isodecyl phosphite, diphenyl tridecyl phosphite, triphenylphosphite, tris(nonylphenyl) phosphite, tris(2,4-di-t-butylphenyl)phosphite, tris(butoxyethyl) phosphite, tetratridecyl4,4′-butylidenebis(3-methyl-6-t-butylphenol) diphosphite,4,4′-isopropylidenediphenol alkyl phosphites (the alkyl group havingabout 12 to 15 carbon atoms), 4,4′-isopropylidenebis (2-t-butylphenol)di(nonylphenyl) phosphite, tris(biphenyl) phosphite, tetra(tridecyl)1,1,3-tris(2-methyl-5-t-butyl-4-hydroxyphenyl) butane diphosphite,tris(3,5-di-t-butyl-4-hydroxyphenyl) phosphite, hydrogenated4,4′-isopropylidenediphenol polyphosphite, bis(octylphenyl) bis[4,4′-butylidenebis(3-methyl-6-t-butylphenol)] 1,6-hexanedioldiphosphite, hexatridecyl 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenol)diphosphite, tris[4,4′-isopropylidenebis(2-t-butylphenol)] phosphite,tris(1,3-distearoyloxyisopropyl) phosphite,9,10-dihydro-9-phosphaphenanthrene-10-oxide,tetrakis(2,4-di-t-butylphenyl)-4,4′-biphenylene diphosphonite, distearylpentaerythritol diphosphite, di(nonylphenyl) pentraerythritoldiphosphite, phenyl 4,4,′-isopropylidenediphenol pentaerythritoldiphosphite, bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite,bis(2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite andphenylbisphenol-A pentaerythritol diphosphite.

[0083] As the antioxidant containing sulfur, it is preferable thatdialkyl thiodipropionates and esters of alkylthiopropionic acids withpolyhydric alcohols are used. As the dialkyl thiodipropionates, dialkylthiodipropionates having alkyl groups having 6 to 20 carbon atoms arepreferable. As the esters of alkylthiopropionic acids with polyhydricalcohols, esters of alkylthiopropionic having an alkyl group having 4 to20 carbon atoms with polyhydric alcohols are preferable. In this case,examples of the polyhydric alcohol for forming the ester of a polyhydricalcohol include glycerol, trimethylolethane, trimethylolpropane,pentaerythritol and trishydroxyethyl isocyanurate.

[0084] Examples of the dialkyl thiodipropionate include dilaurylthiodipropionate, dimyristyl thiodipropionate and distearylthiodipropionate. Examples of the ester of an alkylthiopropionic acidwith a polyhydric alcohol include glycerol tributylthiopropionate,glycerol trioctylthiopropionate, glycerol trilaurylthiopropionate,glycerol tristearylthiopropionate, trimethylolethanetributylthiopropionate, trimethylolethane trioctylthiopropionate,trimethylethane trilaurylthiopropionate, trimethylolethanetristearylthiopropionate, pentaerythritol tetrabutylthiopropionate,pentaerythritol tetraoctylthiopropionate, pentaerythritoltetralaurylthiopropionate and pentaerythritoltetrastearylthiopropionate.

[0085] In the present invention, the secondary antioxidant may be usedsingly or in combination of two or more. The amount of the secondaryantioxidant is selected, in general, in the range of 0.1 to 10 parts byweight per 1 part by weight of the radical scavenger of component (F).When the amount is less than 0.1 part by weight, there is thepossibility that the effect of suppressing coloring is not sufficientlyexhibited. When the amount exceeds 10 parts by weight, the effect of thesecondary antioxidant is not exhibited to the degree expected from theused amount. Moreover, economic disadvantage arises and physicalproperties of adhesion may be adversely affected. From. the standpointof the effect of suppressing coloring, the physical properties ofadhesion and the economy, it is preferable that the amount of theradical scavenger is in the range of 0.5 to 5 parts by weight and morepreferably in the range of 1 to 2 parts by weight per 1 part by weightof the radical scavenger.

[0086] The adhesive compositions II and II′0 of the present inventionmay further comprise various additives conventionally used for adhesivecompositions such as plasticizers, silane coupling agents andultraviolet light absorbents as long as the objects of the presentinvention are not adversely affected, where desired, When adhesivecompositions II and II′ of the present invention having the abovecompositions are applied to easily hydrolyzable materials, degradationof the materials by hydrolysis is suppressed and, in particular,durability under the environment of a high temperature and a highhumidity can be improved. Therefore, it is advantageous that theadhesive compositions of the present invention are applied to films ofacetyl cellulose which are easily hydrolyzed.

[0087] When adhesive compositions I, II and II′ are used for opticalcomponents, it is advantageous that the compositions transmit light.

[0088] In the present invention, a layer comprising any of adhesivecompositions I, II and II′ (referred occasionally to as an adhesivelayer, hereinafter) can be disposed at least on one face of a substrateand the obtained laminate can be used as an adhesive sheet. Examples ofthe substrate include paper substrates such as glassine paper, coatedpaper and cast paper; laminate papers obtained by laminatingthermoplastic resins such as polyethylene on the paper substrates;polyester films such as films of polyethylene terephthalate,polybutylene phthalate and polyethylene naphthalate; polyolefin filmssuch as films of polypropylene and polymethylpentene; plastic films suchas films of polycarbonate and cellulose acetate; and laminate sheetscontaining these films. The substrate is suitably selected in accordancewith the application of the adhesive sheet.

[0089] The above adhesive sheet can be used for transferring theadhesive layer to an adherend or as a component stuck to a desiredadherend. When the adhesive sheet is used in the former application, ingeneral, a substrate sheet is coated with a release agent such as asilicone resin. In this case, the thickness of the substrate sheet isnot particularly limited. In general, the thickness is 20 to 150 μm.

[0090] When the adhesive sheet is used in the latter application, thetype and the thickness of the substrate are suitably selected inaccordance with the application. A conventional release sheet may bedisposed on the adhesive layer, where desired.

[0091] In the above adhesive sheets, the thickness of the adhesive layeris, in general, about 5 to 150 μm and preferably about 10 to 90 μm.

[0092] The adhesive optical components I and II of the present inventioncomprises an optical component and a layer which comprises any ofadhesive compositions I, II and II′ and is disposed at least on one faceof the optical component.

[0093] Preferable examples of the above optical component includepolarizing plates and plates for phase differentiation each having a TACfilm. Examples of the above polarizing plates include polarizing platesused for liquid crystal display apparatuses, for adjustment of quantityof light, for apparatuses using interference of polarized light and foroptical detectors of defects.

[0094] As the application of adhesive optical components I and II of thepresent invention, in particular, it is preferable that the layerscomprising adhesive compositions I, II and II′ are disposed onpolarizing plates and plates for phase differentiation for liquidcrystal cells in liquid crystal display apparatuses.

[0095] When the adhesive composition I of the present invention isapplied to easily hydrolyzable materials, degradation of the materialsby hydrolysis can be suppressed and durability can be improved.Therefore, when the adhesive composition is applied to polarizing platesand plates for phase differentiation for liquid crystal cells,hydrolysis of the TAC film disposed in the plates is suppressed and, inparticular, durability under the environment of a high temperature and ahigh humidity can be improved.

[0096] Adhesive compositions II and II′ provide excellent stressrelaxation without plasticizers. Moreover, when the compositions areapplied to easily hydrolyzable materials, adhesive optical componentshaving excellent qualities can be provided since degradation of thematerials by hydrolysis can be suppressed and degradation of theadhesive compositions themselves can also be suppressed.

EXAMPLES

[0097] The present invention will be described more specifically withreference to examples in the following. However, the present inventionis not limited to the examples.

Example 1

[0098] Into 200 parts by weight of toluene, 100 parts by weight of acopolymer of acrylic esters having a weight-average molecular weight of1,200,000 (the unit of butyl acrylate: 97% by weight and the unit ofacrylic acid: 3% by weight), 0.05 parts by weight of an adduct oftrimethylpropane and tolylene diisocyanate as the crosslinking agent and0.5 parts by weight of 2,6-di-tert-butyl-p-cresol as the phenolderivative were added and a solution of an adhesive was prepared.

[0099] A substrate of a polyethylene terephthalate film having athickness of 38 μm which was coated with a silicone resin on one face[manufactured by LINTEC Corporation; the trade name: SP PET38] wascoated with the solution of an adhesive prepared above on the facecoated with a silicone resin. The substrate coated with the solution ofan adhesive was dried at 100° C. for 1 minute and an adhesive sheethaving an adhesive layer having a thickness of 30 μm was prepared.

[0100] The prepared adhesive sheet was laminated to one face of a TACfilm having a thickness of 80 μm in a manner such that the adhesivelayer was attached to the TAC film. The obtained laminate was aged atthe ordinary temperature for one week and an adhesive optical componenthaving a length of 80 mm and a width of 150 mm was prepared.

[0101] The substrate on the adhesive optical component prepared abovewas removed and the remaining adhesive optical component was stuck to aglass substrate via the exposed adhesive layer.

[0102] The obtained product was subjected to the durability tests underthe condition of a high temperature and under the condition of a hightemperature and a high humidity shown below and the properties wereevaluated. No degradation of the TAC film was confirmed. No lifting orpeeling from the glass substrate was found.

[0103] <Evaluation of the Properties of the Optical Component>

[0104] The durability tests were conducted under a condition of a hightemperature of 100° C. and dry and under a condition of a hightemperature of 80° C. and a high humidity of 90% RH. The degradation ofthe TAC film (turbidity and coloring) and lifting and peeling from theglass substrate were visually observed and the properties of the opticalcomponent were evaluated.

Examples 2 to 7

[0105] Optical components were prepared and the properties wereevaluated in accordance with the same procedures as those conducted inExample 1 except that compounds shown in Table 1 were used in amountsshown in Table 1 as the phenol derivative in place of2,6-di-tert-butyl-p-cresol. The results are shown in Table 1.

[0106] In Table 1, the phenol derivatives are abbreviated as shown inthe following:

[0107] C-1: butylhydroxyanisole

[0108] C-2: stearyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate

[0109] C-3: 4,4′-butylidenebis(3-methyl-6-tert-butylphenol)

[0110] C-4:3,6-dioxaoctamethylenebis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]

[0111] C-5: 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane

[0112] C-6: tetrakis[methylene-3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate]methane TABLE 1 Phenol Evaluation derivative of propertiesamount high temperature type (part by wt.) high temperature and highhumidity Example 2 C-1 1.5 good good Example 3 C-2 2.0 good good Example4 C-3 0.5 good good Example 5 C-4 0.5 good good Example 6 C-5 0.5 goodgood Example 7 C-6 0.5 good good

Example 8

[0113] Into 300 parts by weight of toluene, 100 parts by weight of thecopolymer of acrylic esters which was used in Example 1, 50 parts byweight of a homopolymer of butyl acrylate having a weight-averagemolecular weight of 50,000, 0.05 parts by weight of an adduct oftrimethylpropane and tolylene diisocyanate as the crosslinking agent and0.5 parts by weight of 2,6-di-tert-butyl-p-cresol as the phenolderivative were added and a solution of an adhesive was prepared.

[0114] Subsequently, the same procedures as those conducted in Example 1were conducted. Under the condition of a high temperature and a highhumidity, no degradation of the TAC film was confirmed and no lifting orpeeling from the glass substrate was found.

Example 9

[0115] A solution of an adhesive was prepared in accordance with thesame procedures as those conducted in Example 1 except that 0.05 partsby weight of γ-glycidoxypropyltrimethoxysilane, which is a silanecoupling agent, was further added.

[0116] Subsequently, the same procedures as those conducted in Example 1were conducted. Under the condition of a high temperature and a highhumidity, no degradation of the TAC film was confirmed and no lifting orpeeling from the glass substrate was found.

Comparative Example 1

[0117] The same procedures as those conducted in Example 1 wereconducted except that 2,6-di-tert-butyl-p-cresol was not added. In thedurability tests under the condition of a high temperature and under thecondition of a high temperature and a high humidity, the TAC film becameturbid under the condition of a high temperature and a high humidity andpeeling from the glass substrate took place under the condition of ahigh humidity.

Example 10

[0118] Into 200 parts by weight of toluene, 100 parts by weight of acopolymer of acrylic esters having a weight-average molecular weight of1,200,000 (the unit of butyl acrylate: 97% by weight and the unit ofacrylic acid: 3% by weight), 0.05 parts by weight of an adduct oftrimethylpropane and modified tolylene diisocyanate as the crosslinkingagent and 0.1 part by weight of 2,6-di-tert-butyl-p-cresol as theradical scavenger of a phenolic antioxidant were added and a solution ofan adhesive was prepared.

[0119] A release sheet of a polyethylene terephthalate film having athickness of 38 μm which was coated with a silicone resin on one face[manufactured by LINTEC Corporation; the trade name: SP PET38] wascoated with the solution of an adhesive prepared above on the facecoated with a silicone resin. The release sheet coated with the solutionof an adhesive prepared above was dried at 100° C. for 1 minute and anadhesive sheet having an adhesive layer having a thickness of 30 μm wasprepared.

[0120] The prepared adhesive sheet was laminated to one face of apolarizing plate having a three-layer laminate structure composed of afilm of triacetylcellulose, a film of polyvinyl alcohol and a film oftriacetylcellulose laminated in this order in a manner such that thelayer of the adhesive was attached to the polarizing plate. The obtainedlaminate was aged at the ordinary temperature for one week and anadhesive optical component having a length of 80 mm and a width of 150mm was prepared.

[0121] The release sheet on the adhesive optical component preparedabove was removed and the remaining adhesive optical component was stuckto both faces of a glass plate for a liquid crystal cell via the exposedadhesive layer so that an orthogonal Nicol was formed.

[0122] The properties of the obtained optical component was evaluated inaccordance with the methods described in the following. The results ofthe evaluation are shown in Table 2.

[0123] <Evaluation of the properties of the optical component>

[0124] The durability tests were conducted under the condition of a hightemperature of 100° C. and dry for 1,000 hours and under the conditionof a high temperature of 80° C. and a high humidity of 90% RH for 1,000hours. The results were evaluated as follows:

[0125] (1) Resistance of a TAC Film to Hydrolysis

[0126] The condition of degradation (turbidity and coloring) of a TACfilm was evaluated by visual observation. When no lifting or peeling wasfound, the resistance to hydrolysis was evaluated as good. When liftingand peeling were found, the resistance to hydrolysis was evaluated aspoor.

[0127] (2) Durability (Resistance of an Adhesive to Degradation)

[0128] The presence or the absence of lifting and peeling of an opticalcomponent from a glass plate was visually observed. When no lifting orpeeling was found, the durability was evaluated as good. When liftingand peeling were found, the durability was evaluated as poor.

[0129] (3) Effect of Suppressing Difference in Brightness

[0130] Difference in brightness at peripheral portions and at innerportions (the picture frame phenomenon) of a polarizing plate wasvisually observed. When no picture frame phenomenon, i.e., no differencein brightness, was found, the effect of suppressing difference inbrightness was evaluated as good. When the picture frame phenomenon,i.e., the difference in brightness, was found, the effect of suppressingdifference in brightness was evaluated as poor.

[0131] (4) Resistance to Coloring of an Adhesive

[0132] An adhesive layer was formed on a polarizing plate and theresultant laminate was stuck to a glass plate. The obtained opticalcomponent was placed under the condition of a high temperature of 100°C. and dry for 1,000 hours or under the condition of a high temperatureof 800° C. and a high humidity of 90% RH for 1,000 hours. The change incolor of the optical component was obtained by the measurement of thedegree of yellowing (b*) and the degree of redding (c*) in accordancewith the method of Japanese Industrial Standard K 7103 using a colordifference meter [manufactured by NIPPON DENSHOKU Co., Ltd.; SQ-2000].The resistance to coloring was evaluated in accordance with thefollowing criteria:

[0133] good: a change smaller than 0.5

[0134] fair: a change of 0.5 or greater and smaller than 1.0

[0135] poor: a change of 1.0 or greater

Example 11

[0136] An optical component was prepared and evaluated in accordancewith the same procedures as those conducted in Example 10 except that0.1 part by weight of an antioxidant containing phosphorus which was a4,4′-isopropylidenediphenol alkyl phosphite [manufactured by ASAHI DENKAKOGYO Co., Ltd.; the trade name: ADEKASTAB 1500] was further added asthe secondary antioxidant. The results are shown in Table 2.

Example 12

[0137] An optical component was prepared and evaluated in accordancewith the same procedures as those conducted in Example 10 except that 25parts by weight of a homooligomer of butyl acrylate having aweight-average molecular weight of 4,000 (Mw/Mn=1.5) and 0.05 parts byweight of the antioxidant containing phosphorus used in Example 11[ADEKASTAB 1500] were further added. The results are shown in Table 2.

Example 13

[0138] An optical component was prepared and evaluated in accordancewith the same procedures as those conducted in Example 12 except that0.05 parts by weight of an antioxidant containing sulfur which wasdimyristyl thiodipropionate [manufactured by ASAHI DENKA KOGYO Co.,Ltd.; the trade name: ADEKASTAB AO-503A] was used in place of theantioxidant containing phosphorus “ADEKASTAB 1500”. The results areshown in Table 2.

Example 14

[0139] An optical component was prepared and evaluated in accordancewith the same procedures as those conducted in Example 10 except that 25parts by weight of a homooligomer of butyl acrylate having aweight-average molecular weight of 10,000 (Mw/Mn=1.6) was further addedand 0.1 part by weight of a phenolic antioxidant [manufactured bySUMITOMO KAGAKU KOGYO Co., Ltd.; the trade name: SUMILIZER GS] was usedin place of 0.1 part by weight of 2,6-di-t-butyl-p-cresol. The resultsare shown in Table 2.

Example 15

[0140] An optical component was prepared and evaluated in accordancewith the same procedures as those conducted in Example 14 except that0.05 parts by weight of an amine photostabilizer which wastetrakis(2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate[manufactured by ASAHI DENKA KOGYO Co., Ltd.; the trade name: ADEKASTABLA-57] was used in place of 0.1 part by weight of the phenolicantioxidant “SUMILIZER GS”. The results are shown in Table 2.

Example 16

[0141] An optical component was prepared and evaluated in accordancewith the same procedures as those conducted in Example 15 except that0.05 parts by weight of an antioxidant containing phosphorus which wasbis(2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite[manufactured by ASAHI DENKA KOGYO Co., Ltd.; the trade name: ADEKASTABPEP-36] was further added. The results are shown in Table 2.

Example 17

[0142] An optical component was prepared and evaluated in accordancewith the same procedures as those conducted in Example 10 using 100parts by weight of a copolymer of acrylic esters having a weight-averagemolecular weight of 1,200,000 (the unit of butyl acrylate: 96.9% byweight, the unit of acrylic acid: 3% by weight and the unit of apolymerizable phenolic antioxidant [manufactured by SUMITOMO KAGAKUKOGYO Co., Ltd.; the trade name: SUMILIZER GM]: 0.1% by weight), 25parts by weight of a homooligomer of butyl acrylate having aweight-average molecular weight of 10,000, 0.05 parts by weight of anadduct of trimethylolpropane and modified tolylene diisocyanate and 0.05parts by weight of the antioxidant containing phosphorus “ADEKASTAB1500” which was used above. The results are shown in Table 2.

Example 18

[0143] An optical component was prepared and evaluated in accordancewith the same procedures as those conducted in Example 10 except that0.5 parts by weight of hydroquinone which was a polymerization inhibitorwas used in place of 0.1 part by weight of 2,6-di-t-butyl-p-cresol. Theresults are shown in Table 2.

Comparative Example 2

[0144] An optical component was prepared and evaluated in accordancewith the same procedures as those conducted in Example 10 except that2,6-di-t-butyl-p-cresol was not used. The results are shown in Table 2.

Comparative Example 3

[0145] An optical component was prepared and evaluated in accordancewith the same procedures as those conducted in Example 12 except thateither 2,6-di-t-butyl-p-cresol or the antioxidant containing phosphorus“ADEKASTAB 1500” was not used. The results are shown in Table 2. TABLE 2Evaluation of properties of optical component effect resistance ofsuppressing resistance to to hydrolysis of difference in coloring of TACfilm durability brightness adhesive Example 10 good good good fairExample 11 good good good good Example 12 good good good good Example 13good good good good Example 14 good good good good Example 15 good goodgood fair Example 16 good good good good Example 17 good good good goodExample 18 good good good fair Comparative poor poor good good Example 2Comparative poor poor poor good Example 3

[0146] In Examples 10 to 18, the resistance to hydrolysis of a TAC film,the durability and the effect of suppressing difference in brightnesswere good. In Examples 11 to 14, 16 and 17, the resistance to coloringof an adhesive was good. In Example 14, although the phenolicantioxidant was used alone without secondary antioxidants, theresistance to coloring of an adhesive was good since the specificantioxidant causing little coloring was used. In Example 17, thepolymerizable antioxidant was used as the phenolic antioxidant andintroduced into the copolymer of acrylic esters by copolymerization. Theoptical component exhibiting excellent properties could be obtained.

[0147] In contrast, in Comparative Examples 2 and 3, hydrolysis of theTAC film took place and coloring of the film was observed since noantioxidants were added. Portions of the adhesive optical component werepeeled from the glass plate. In Comparative Example 3, the difference inbrightness was found in the polarizing plate.

What is claimed is:
 1. An adhesive sheet comprising an adhesivecomposition disposed on at least one face of a film of acetyl cellulose,the adhesive sheet being produced by coating a solution of the adhesivecomposition on said face of said film and drying the solution to form alaminate, said adhesive composition comprises (A) a copolymer of(meth)acrylic esters, (B) a crosslinking agent and (C) a phenolcompound.
 2. The adhesive sheet according to claim 1, wherein the phenolcompound (C) is at least one compound selected from the group consistingof 2,6-di-tert-butyl-p-cresol, butylhydroxyanisole, stearylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,4,4′-butylidenebis(3-methyl-6-tert-butylphenol),3,6-dioxaoctamethylenebis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, wherein thecrosslinking agent (B) is in an amount of 0.001 to 50 parts by weightper 100 parts by weight of the copolymer (A).
 3. An adhesive sheetcomprising an adhesive composition disposed on at least one face of afilm of acetyl cellulose, the adhesive sheet being produced by coating asolution of the adhesive composition on one face of a substrate, saidface of said substrate being coated with a releasing agent, drying thesolution to form a laminate and transferring the adhesive composition tothe face of the film of the acetyl cellulose, said adhesive compositioncomprising (A) a copolymer of (meth)acrylic esters, (B) a crosslinkingagent and (C) a phenol compound.
 4. The adhesive sheet according toclaim 3, wherein the phenol compound (C) is at least one compoundselected from the group consisting of 2,6-di-tert-butyl-p-cresol,butylhydroxy-anisole, stearyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 4,4′-butylidenebis(3-methyl-6-tert-butylphenol),3,6-dioxaoctamethylenebis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, wherein thecrosslinking agent (B) is in an amount of 0.001 to 50 parts by weightper 100 parts by weight of the copolymer (A).
 5. The adhesive sheetaccording to claim 3, wherein the adhesive composition comprises 0.01 to10 parts by weight of the phenol compound (C) per 100 parts by weight ofcomponent (A).
 6. An adhesive optical component comprising an opticalcomponent and a layer which comprises an adhesive composition, saidadhesive composition being disposed on at least one face of the opticalcomponent by coating a solution of the adhesive composition on said faceof the optical component and drying the solution to form a laminate,said adhesive composition comprising (A) a copolymer of (meth)acrylicesters, (B) a crosslinking agent and (C) a phenol compound.
 7. Theadhesive optical component according to claim 6, wherein the phenolcompound (C) is at least one compound selected from the group consistingof 2,6-di-tert-butyl-p-cresol, butylhydroxyanisole, stearylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,4,4′-butylidenebis(3-methyl-6-tert-butylphenol),3,6-dioxaoctamethylenebis-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, wherein thecrosslinking agent (B) is in an amount of 0.001 to 50 parts by weightper 100 parts by weight of the copolymer (A).
 8. An adhesive opticalcomponent comprising an optical component and a layer which comprises anadhesive composition, a solution of said adhesive composition beingdisposed on one face of a substrate, said face of said substrate beingcoated with a releasing agent, drying the solution to form a laminateand transferring the adhesive composition to said face of the opticalcomponent, said adhesive composition comprising (A) a copolymer of(meth)acrylic esters, (B) a crosslinking agent and (C) a phenolcompound.
 9. The adhesive optical component according to claim 8,wherein the phenol compound (C) is at least one compound selected fromthe group consisting of 2,6-di-tert-butyl-p-cresol, butylhydroxyanisole,stearyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,4,4′-butylidenebis(3-methyl-6-tert-butylphenol),3,6-dioxaoctamethylenebis[3-(3-tert-butyl-4-hydroxy-5-methyl-phenyl)propionate],and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, wherein thecrosslinking agent (B) is in an amount of 0.001 to 50 parts by weightper 100 parts by weight of the copolymer (A).
 10. The adhesive opticalcomponent according to claim 8, wherein the adhesive compositioncomprises 0.01 to 10 parts by weight of the phenol compound (C) per 100parts by weight of component (A).
 11. The adhesive optical componentaccording to claim 8, wherein the optical component is a polarizingplate.
 12. The adhesive optical component according to claim 8, whereinthe optical component is a plate for phase differentiation.
 13. Theadhesive optical component according to claim 8, wherein after drying,the laminate is aged at ordinary temperature for at least a week. 14.The adhesive optical component according to claim 8, wherein thecopolymer of (meth)acrylic esters (A) is a copolymer of (a) at least onemonomer selected from the group consisting of methyl(meth)acrylate,ethyl(meth)acrylate, propyl(meth)acrylate, butyl(meth)acrylatepentyl(meth)acrylate, hexyl(meth)acrylate and cyclohexyl (meth)acrylate,and (b) at least one monomer selected from the group consisting of2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth) acrylate,3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate,acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide,N-methylolacrylamide, N-methylolmethacrylamide, monomethylaminoethyl(meth)acrylate, monoethylaminoethyl (meth)acrylate,monomethylaminopropyl (meth)acrylate, monoethylaminopropyl(meth)acrylate, acrylic acid, methacrylic acid, crotonic acid, maleicacid, itaconic acid and citraconic acid.
 15. The adhesive opticalcomponent according to claim 14, wherein the crosslinking agent (B) is apolyisocyanate compound.
 16. The adhesive optical component according toclaim 15, wherein the phenol compound (C) is selected from the groupconsisting of 2,6-di-tert-butyl-p-cresol and4,4′-butylidenebis(3-methyl-6-tert-butylphenol).
 17. An adhesive opticalcomponent comprising an optical component and a layer which comprises anadhesive composition, said adhesive composition being disposed on atleast one face of the optical component by coating a solution of theadhesive composition on said face of the optical component and dryingthe solution to form a laminate, said adhesive composition comprising(D) a copolymer of (meth)acrylic esters having a weight-averagemolecular weight of 500,000 to 2,500,000, (E) a crosslinkiug agent and(F) a radical scavenger.
 18. An adhesive optical component comprising anoptical component and a layer which comprises an adhesive composition, asolution of said adhesive composition being disposed on one face of asubstrate, said face of said substrate being coated with a releasingagent, drying the solution to form a laminate and transferring theadhesive composition to the face of the optical component, said adhesivecomposition comprising (D) a copolymer of (meth)acrylic esters having aweight-average molecular weight of 500,000 to 2,500,000, (E) acrosslinking agent and (F) a radical scavenger.
 19. The adhesive opticalcomponent according to claim 18, wherein the optical component is apolarizing plate.
 20. The adhesive optical component according to claim18, wherein the optical component is a plate for phase differentiation.21. An adhesive optical component comprising an optical component and alayer which comprises an adhesive composition, said adhesive compositionbeing disposed on at least one face of the optical component by coatinga solution of the adhesive composition on said face of the opticalcomponent and drying the solution to form a laminate, said adhesivecomposition comprising (D′) a mixture of a copolymer of (meth)acrylicesters having a weight-average molecular weight of 500,000 to 2,500,000and an oligomer of (meth)acrylic esters having a weight-averagemolecular weight of 1,000 to 10,000 in amounts such that a ratio of theamounts by weight of the copolymer to the oligomer is 100:5 to 100:100,(E) a crosslinking agent and (F) a radical scavenger.
 22. An adhesiveoptical component comprising an optical component and a layer whichcomprises an adhesive composition, a solution of said adhesivecomposition being disposed on one face of a substrate, said face of saidsubstrate being coated with a releasing agent, drying the solution toform a laminate and transferring the adhesive composition to the face ofthe optical component, said adhesive composition comprising (D′) amixture of a copolymer of (meth)acrylic esters having a weight-averagemolecular weight of 500,000 to 2,500,000 and an oligomer of(meth)acrylic esters having a weight-average molecular weight of 1,000to 10,000 in amounts such that a ratio of the amounts by weight of thecopolymer to the oligomer is 100:5 to 100:100, (E) a crosslinking agentand (F) a radical scavenger.
 23. The adhesive optical componentaccording to claim 22, wherein the optical component is a polarizingplate.
 24. The adhesive optical component according to claim 22, whereinthe optical component is a plate for phase differentiation.